JP2006252424A - Program, information storage medium and image generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a program, an information storage medium and an image generation system for generating a high quality image, and for attaining high quality shading expressions in a handwritten image. <P>SOLUTION: This image generation system for generating an image viewed from a given point of view in an object space is provided with a geometry processing part 122 for performing geometry processing by perspectively projecting an object on a screen coordinate system, a screen coordinate acquiring part 116 for acquiring the vertex screen coordinates at the respective vertices of the object after the geometry processing, a texture coordinate arithmetic part 118 for performing the addition or subtraction processing of normal vector information at the respective vertices of the object to the acquired vertex screen coordinates, and for calculating texture coordinates at the respective vertices of the object and a texture mapping part 124 for mapping the given texture on the object based on the calculated texture coordinates. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a program, an information storage medium, and an image generation system.

  Conventionally, an image generation system (game system) that generates an image that can be seen from a virtual camera (a given viewpoint) in an object space that is a virtual three-dimensional space is known. Popular. Taking an image generation system capable of enjoying a role-playing game (RPG) as an example, a player operates a character (object), which is his or her own character, and moves it on a map in the object space to play against an enemy character. Play games by interacting with other characters or visiting various towns.

  In such an image generation system, a pattern image (tone image or tone texture) representing a pattern (for example, mesh, grid, hatching, etc.) used in comics or animation called a screen tone is used as an object. Mapping may be used to express shading or shading. In texture mapping using such a pattern image, for example, handwritten image expression can be performed.

By the way, for example, when a shadow (shade) is expressed on an object having a curved surface such as a sphere by performing texture mapping of the pattern image as described above, the shadow line should be originally drawn along the surface shape of the object. . However, simply mapping the pattern image to the object results in a uniform shadow line, and the handwritten tone cannot be expressed sufficiently.
JP 2001-319244 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to generate a high-quality image, for example, a program and information capable of realizing a high-quality shadow expression in a handwritten image To provide a storage medium and an image generation system.

  The present invention is an image generation system for generating an image viewed from a given viewpoint in an object space, a geometry processing unit that performs perspective processing by projecting an object onto a screen coordinate system, and a post-geometry processing A screen coordinate acquisition unit that acquires the vertex screen coordinates of each vertex of the object, and the normal vector information for each vertex of the object is added to or subtracted from the acquired vertex screen coordinates to obtain the object A texture coordinate calculation unit that obtains texture coordinates for each of the vertices, and a texture mapping unit that maps a given texture to the object based on the obtained texture coordinates. The present invention also relates to a program that causes a computer to function as each of the above-described units. The present invention also relates to an information storage medium that can be read by a computer and stores (records) a program that causes the computer to function as each of the above-described units.

  According to the present invention, when obtaining the texture coordinates, mapping is performed by adding or subtracting normal vector information at each vertex to the vertex screen coordinates of each vertex of the object projected on the screen. The tone (texture) can be deformed along the shape of the object. That is, according to the present invention, when a tone is mapped onto an object surface having a curved surface, it is possible to express a texture as if it was handwritten along the shape of the object (object) to be mapped.

  In the image generation system, the program, and the information storage medium according to the present invention, the normal vector information is an absolute value of a coordinate component of a normal vector of each vertex of the object in the viewpoint coordinate system or the screen coordinate system. It may be. In this way, the texture of the handwritten tone can be sufficiently expressed without the change amount of the texture coordinates by the addition or subtraction process of the normal vector information being too large.

  In the image generation system, program, and information storage medium according to the present invention, the normal vector information may be obtained by multiplying the absolute value of the coordinate component of the normal vector by a given correction coefficient. Good. In this way, the degree of texture change can be adjusted so that a handwritten tone-specific texture is produced.

  In the image generation system, the program, and the information storage medium according to the present invention, the screen coordinate acquisition unit acquires a reference point screen coordinate for a reference point set for the object in addition to the vertex screen coordinate. The texture coordinate calculation unit adds or subtracts normal vector information for each vertex of the object with respect to the difference between the vertex screen coordinates and the reference point screen coordinates, You may make it obtain | require the texture coordinate about a vertex. In this way, since the reference point is set for each object, the texture coordinates are obtained so as to follow these movements even when the viewpoint or the object moves. Accordingly, it is possible to generate a high-quality image in which unnaturalness due to the movement of the camera or the object does not easily occur. For example, it is possible to realize a high-quality shadow expression in a handwritten image.

  In the image generation system, the program, and the information storage medium according to the present invention, the texture coordinate calculation unit calculates the texture coordinates according to a distance difference in the depth direction in the viewpoint coordinate system between each vertex of the object and the reference point. You may make it correct | amend. Since each vertex of the object has a depth coordinate value even after geometry processing, when the viewpoint moves, an object close to the viewpoint moves fast on the screen, and an object far from the viewpoint moves slowly on the screen. For this reason, if a texture is mapped across objects that have a distance difference from each other in the depth direction from the reference point, unnaturalness tends to occur in the degree of change in the texture display when the viewpoint or the object itself moves. Become. Therefore, by changing the texture coordinates according to the distance difference in the depth direction in the viewpoint coordinate system or screen coordinate system between each vertex of the object and the reference point, the display change of the texture follows the movement of the viewpoint, and the image is not correct. By preventing it from becoming natural, it is possible to realize high-quality image expression.

  In this case, the texture coordinates are corrected so that the vertex is closer to the depth in the depth direction from the reference point, and the correction amount is smaller, and the vertex is farther from the reference point in the depth direction. be able to. For example, the texture coordinates may be corrected based on the ratio of the perspective division value of each vertex of the object and the perspective division value of the reference point.

  In the image generation system, program, and information storage medium according to the present invention, the texture coordinate calculation unit adds a variable that changes randomly or periodically to the texture coordinates to change the texture coordinates. May be. In this way, it is possible to express a picture shift unique to handwriting as in each frame image of handwritten animation. In this case, the variable may change according to at least one of time, viewpoint movement information, and a game event. For example, when the viewpoint moves, the frame image changes greatly, so by adding a variable whose value changes according to the movement information of the viewpoint and changing the texture coordinates, it is possible to sufficiently express the handwritten texture. .

  Hereinafter, this embodiment will be described. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. In addition, all the configurations described in the present embodiment are not necessarily essential configuration requirements of the present invention.

1. Configuration FIG. 1 shows an example of a functional block diagram of an image generation system (game system) of the present embodiment. Note that the image generation system of the present embodiment may have a configuration in which some of the components (each unit) in FIG. 1 are omitted.

  The operation unit 160 is for a player to input operation data of a player object (player character operated by the player), and the function is realized by a lever, a button, a steering, a microphone, a touch panel display, or a casing. it can. The storage unit 170 serves as a work area for the processing unit 100, the communication unit 196, and the like, and its function can be realized by a RAM (VRAM) or the like.

  The information storage medium 180 (computer-readable medium) stores programs, data, and the like, and functions as an optical disk (CD, DVD), magneto-optical disk (MO), magnetic disk, hard disk, and magnetic tape. Alternatively, it can be realized by a memory (ROM). The processing unit 100 performs various processes of the present embodiment based on a program (data) stored in the information storage medium 180. That is, the information storage medium 180 stores a program for causing a computer to function as each unit of the present embodiment (a program for causing a computer to execute processing of each unit).

  The display unit 190 outputs an image generated according to the present embodiment, and its function can be realized by a CRT, LCD, touch panel display, HMD (head mounted display), or the like. The sound output unit 192 outputs the sound generated by the present embodiment, and its function can be realized by a speaker, headphones, or the like.

  The portable information storage device 194 stores player personal data, game save data, and the like. Examples of the portable information storage device 194 include a memory card and a portable game device. The communication unit 196 performs various controls for communicating with the outside (for example, a host device or other image generation system), and functions thereof are hardware such as various processors or communication ASICs, programs, and the like. It can be realized by.

  Note that a program (data) for causing a computer to function as each unit of this embodiment is distributed from the information storage medium of the host device (server) to the information storage medium 180 (storage unit 170) via the network and communication unit 196. May be. Use of the information storage medium of such a host device (server) can also be included in the scope of the present invention.

  The processing unit 100 (processor) performs processing such as game processing, image generation processing, or sound generation processing based on operation data and programs from the operation unit 160. Here, as the game process, a process for starting a game when a game start condition is satisfied, a process for advancing the game, a process for placing an object such as a character or a map, a process for displaying an object, and a game result are calculated. There is a process or a process of ending a game when a game end condition is satisfied. The processing unit 100 performs various processes using the main storage unit 172 in the storage unit 170 as a work area. The functions of the processing unit 100 can be realized by hardware such as various processors (CPU, DSP, etc.), ASIC (gate array, etc.), and programs.

  The processing unit 100 includes an object space setting unit 110, a movement / motion processing unit 112, a virtual camera control unit 114, a screen coordinate acquisition unit 116, a texture coordinate calculation unit 118, an image generation unit 120, and a sound generation unit 130. Note that some of these may be omitted.

  The object space setting unit 110 includes various objects (primitive surfaces such as polygons, free-form surfaces, and subdivision surfaces) representing display objects such as characters, buildings, stadiums, cars, trees, columns, walls, and maps (terrain). A part object or a model object composed of a plurality of part objects) is set in the object space. In other words, the position and rotation angle of the object in the world coordinate system (synonymous with direction and direction) are determined, and the rotation angle (rotation angle around the X, Y, and Z axes) is determined at that position (X, Y, Z). Arrange objects.

  The movement / motion processing unit 112 performs a movement / motion calculation (movement / motion simulation) of an object (such as a character, a car, or an airplane). That is, based on operation data input by the player through the operation unit 160, a program (movement / motion algorithm), various data (motion data), or the like, the object is moved in the object space, or the object is moved (motion, animation). ) Is performed. Specifically, a simulation process for sequentially obtaining object movement information (position, rotation angle, speed, or acceleration) and motion information (position or rotation angle of each part object) every frame (1/60 second). I do. A frame is a unit of time for performing object movement / motion processing (simulation processing) and image generation processing.

  The virtual camera control unit 114 performs a virtual camera (viewpoint) control process for generating an image viewed from a given (arbitrary) viewpoint in the object space. Specifically, a process for controlling the position (X, Y, Z) or the rotation angle (rotation angle about the X, Y, Z axes) of the virtual camera (process for controlling the viewpoint position and the line-of-sight direction) is performed.

  For example, when an object (eg, character, ball, car) is photographed from behind using a virtual camera, the position or rotation angle of the virtual camera (the direction of the virtual camera is set so that the virtual camera follows changes in the position or rotation of the object. ) To control. In this case, the virtual camera can be controlled based on information such as the position, rotation angle, or speed of the object obtained by the movement / motion processing unit 112. Alternatively, the virtual camera may be controlled to rotate at a predetermined rotation angle or to move along a predetermined movement path. In this case, the virtual camera is controlled based on the virtual camera data for specifying the position (movement path) or rotation angle of the virtual camera. When there are a plurality of virtual cameras (viewpoints), the above control process is performed for each virtual camera.

  The screen coordinate acquisition unit 116 performs processing for acquiring screen coordinates (X, Y coordinates) converted into texture coordinates (U, V coordinates) for mapping a tone texture (pattern image) to an object. Specifically, the screen coordinates of each vertex of the object subjected to geometry processing (coordinate-transformed by perspective projection onto the screen coordinate system) are acquired as vertex screen coordinates.

  The texture coordinate calculation unit 118 performs processing for obtaining the texture coordinates of the texture mapped to the object. Specifically, the texture coordinate A is obtained by adding or subtracting normal vector information (normal vector information) for each vertex of the object to the vertex screen coordinates acquired by the screen coordinate acquisition unit 116. At this time, the coordinate component (X, Y coordinate component) of the normal vector of each vertex of the object in the camera coordinate system or the screen coordinate system (normal vector representing the orientation of the surface; the normal vector set at the vertex of the object) ) Is converted into an absolute value (for example, a value range (−1.0 to 1.0) becomes a value range (0.0 to 1.0)), and a given correction coefficient is multiplied by the absolute value. This can be used as normal vector information. When using the coordinate component of the normal vector in the screen coordinate system, it is desirable to convert the length of the normal vector after perspective transformation into a unit vector. If the coordinate component of the normal vector is converted into an absolute value in this way, addition or subtraction processing can be performed depending on the sign of the correction coefficient, and the degree of shape correction can be easily controlled. .

  For example, the vertex screen coordinate is P (x, y), the texture size (pixel information) of the tone texture is (tx × ty), the vertex normal vector coordinate component is N (Nx, Ny, Nz), and the correction coefficient Is M (Mx, My), the texture coordinates A (ax, ay) obtained for the vertex screen coordinates P are obtained by the following equation.

A (ax, ay) = (x / tx + (| Nx | * Mx), y / ty + (| Ny | * My)) (1A)
In addition, when performing an addition process, it is realizable by making correction coefficient M (Mx, My) into a positive value, and when performing a subtraction process, making correction coefficient M (Mx, My) into a negative value. Can be represented by

  In addition, the texture coordinate calculation unit 118 performs a difference process on the vertex screen coordinates acquired by the screen coordinate acquisition unit 116 and the screen coordinates of the reference point set for the object (reference point screen coordinates) to obtain the tone texture. You may obtain | require a texture coordinate about each vertex of the object used as mapping object. In this case, the screen coordinate acquisition unit 116 acquires screen coordinates obtained by geometry processing of the reference points set for the object as reference point screen coordinates.

  For example, if the reference point screen coordinates are B (bx, by), the texture coordinates A1 (ax1, ay1) are obtained as in the following equation.

A1 (ax1, ay1) = ((x-bx) / tx, (y-by) / ty) (2A)
Then, when the calculation method of the above equation (2A) is applied to the above equation (1A), the texture coordinates A2 (ax2, ay2) are expressed by the following equation.

A2 (ax2, ay2) = ((x-bx) / tx + (| Nx | * Mx), (y-by) / ty + (| Ny | * My)) (3A)
In addition, the texture coordinate calculation unit 118 performs a process of correcting the texture coordinates in accordance with the distance difference in the depth direction in the camera coordinate system (viewpoint coordinate system) or the screen coordinate system between each vertex of the object and the reference point. Specifically, the correction amount (correction degree) is smaller as the vertex is closer to the depth direction from the reference point, and the correction amount is larger so that the vertex is farther from the reference point in the depth direction. The correction calculation is performed on the texture coordinates obtained in (1). In this case, the perspective division value can be used to take into account the distance in the depth direction between the vertex and the reference point.For example, the ratio between the perspective division value of each vertex of the object and the perspective division value of the reference point Based on this, texture coordinates can be corrected. For example, if the perspective division values of the vertex and the reference point of the object are 1 / w and 1 / bw, respectively, the distance correction value d of the texture coordinate A and the corrected texture coordinate A3 (ax3, ay3) are as shown in the following equation: Desired.

d = (1 / bw) / (1 / w) = w / bw (4A)
A3 (ax3, ay3) = ((x-bx * d) / tx + (| Nx | * Mx), (y-by * d) / ty + (| Ny | * My)) (5A)
The texture coordinate calculation unit 118 adds a motion correction value (variable) that changes randomly or periodically to the texture coordinate obtained by the above equation (5A) and maps the tone texture to the texture coordinate. The process which changes is performed. For example, if the motion correction value is m (mx, my), the texture coordinates A4 (ax4, ay4) subjected to the motion correction processing are obtained as in the following equation.

A4 (ax4, ay4) = (mx + (x-bx * d) / tx + (| Nx | * Mx), my + (y-by * d) / ty + (| Ny | * My)) (6A)
The motion correction process may be performed on the texture coordinates A or the texture coordinates A2 obtained by the above expression (1A) or (3A).

  The image generation unit 120 performs drawing processing based on the results of various processes (game processing) performed by the processing unit 100, thereby generating an image and outputting the image to the display unit 190. In the case of generating a so-called three-dimensional game image, first, geometric processing such as coordinate transformation (world coordinate transformation, camera coordinate transformation), clipping processing, or perspective transformation is performed, and drawing data ( The position coordinates, texture coordinates, color data, normal vector, α value, etc.) of the vertexes of the primitive surface are created. Then, based on the drawing data (object data), the image information can be stored in units of pixels such as the drawing buffer 174 (frame buffer, intermediate buffer, etc.) of the object (one or a plurality of primitive surfaces) after perspective transformation (after geometry processing). Draw in the buffer (VRAM). Thereby, an image that can be seen from the virtual camera (given viewpoint) in the object space is generated. When there are a plurality of virtual cameras (viewpoints), an image that can be seen from each virtual camera is generated as a divided image so that it can be displayed on one screen.

  The image generation unit 120 includes a geometry processing unit 122, a texture mapping unit 124, and a translucent processing unit 126.

  The geometry processing unit 122 performs geometry processing on the object. More specifically, geometric processing such as coordinate transformation, clipping processing, perspective transformation, or light source calculation is performed. Then, the object data after the geometry processing (after perspective transformation) (position coordinates of the vertex of the object, texture coordinates, color data, normal vector, or 癇 l, etc.) is stored in the main storage unit 172 of the storage unit 170. .

  The texture mapping unit 122 performs processing for mapping the texture (texel value) stored in the texture storage unit 176 to the object. Specifically, the texture (surface properties such as color and α value) is read from the texture storage unit 176 using texture coordinates or the like set (given) to the vertex of the object. Then, a texture that is a two-dimensional image or pattern is mapped to the object. In this case, processing for associating pixels and texels, bilinear interpolation (texel interpolation), and the like are performed.

  The translucent processing unit 126 performs a translucent compositing process (usually α blending, α addition blending, α subtraction blending, or the like) based on the α value (A value). For example, in the case of normal α blending, the following processing is performed.

R _Q = (1−α) × R ₁ + α × R ₂ (1)
G _Q = (1−α) × G ₁ + α × G ₂ (2)
B _Q = (1−α) × B ₁ + α × B ₂ (3)
On the other hand, in the case of addition α blending, the following processing is performed.

R _Q = R ₁ + α × R ₂ (4)
G _Q = G ₁ + α × G ₂ (5)
B _Q = B ₁ + α × B ₂ (6)
Here, R ₁ , G ₁ , B ₁ are RGB components of an image (original image) already drawn in the drawing buffer 174, and R ₂ , G ₂ , B ₂ should be drawn in the drawing buffer 174. This is the RGB component of the image. R _Q , G _Q , and B _Q are RGB components of an image obtained by α blending. The α value is information that can be stored in association with each pixel (texel, dot), for example, plus alpha information other than color information. The α value can be used as mask information, translucency (equivalent to transparency and opacity), bump information, and the like.

  The translucent processing unit 126 performs a process of translucently combining an image (original image) mapped with a normal texture and an image (tone map image) mapped with a tone texture. Specifically, first, a first subtractive tone map image that has been subjected to subtraction translucency processing for subtracting the luminance value of a color image of a predetermined color from the luminance value of the tone map image, and the luminance value of the tone map image from the luminance value of the color image. And a second subtraction tone map image subjected to the subtraction translucent process for subtracting. Then, the original image and the first subtraction tone map image are subjected to addition semi-transparency processing, and the second subtraction tone map image is subjected to subtraction translucency processing from the image after the addition semi-transparency processing, thereby obtaining the original image and the tone map image. Translucent composition. That is, in the tone map image, an addition translucent process is performed for colors brighter than the respective color components of the color image, and a subtractive translucent process is performed for colors darker than the respective color components of the color image. As a result, the influence of the tone texture pattern is not excessively exerted on each color component of the original image, and the texture of the hand-drawn picture can be expressed.

  In this case, an intermediate color (for example, gray (R, G, B) = (0.5, 0.5, 0.5)) can be used as the color image of the predetermined color.

  In this case, the blend ratio (α value) in the translucent synthesis process of the original image and the tone map image can be obtained as follows. First, the original image is converted to gray scale by CLUT (Color Look Up Table) conversion, and the blend ratio can be obtained from the luminance value of the color component of the gray scale image. Note that power correction may be performed on the blend ratio (α value) obtained at this time. In this way, when performing shade expression using a tone texture, the darker portion of the original image is emphasized and the natural color blur specific to the handwritten picture can be expressed.

  The sound generation unit 130 performs sound processing based on the results of various processes performed by the processing unit 100, generates game sounds such as BGM, sound effects, or sounds, and outputs the game sounds to the sound output unit 192.

  Note that the image generation system of the present embodiment may be a system dedicated to the single player mode in which only one player can play, or may be a system having a multiplayer mode in which a plurality of players can play. Further, when a plurality of players play, game images and game sounds to be provided to the plurality of players may be generated using one terminal, or connected via a network (transmission line, communication line) or the like. Alternatively, it may be generated by distributed processing using a plurality of terminals (game machine, mobile phone).

2. Next, the method of this embodiment will be described with reference to the drawings. In the following, the case where the method of the present embodiment is employed when expressing the shadow of an object in a game image will be mainly described. However, the method of the present embodiment is not limited to the expression of a shadow in such a game image. It can be applied to various image expressions.

2.1 Texture Coordinate Calculation Method When creating an image by handwriting, for example, when expressing the shadow of a sphere in handwritten animation, the line drawing for expressing the shadow should be expressed along the sphere. is there. However, if the tone texture is simply mapped to the object, for example, if the tone texture of a linear pattern is mapped to the object for shading expression as shown in FIG. I cannot express enough.

  Therefore, in the present embodiment, a technique is adopted in which the tone texture pattern is deformed and mapped so as to follow the shape of the object. In particular, the present embodiment focuses on the normal vector (normal vector) of the vertex of the object. The normal vector of each vertex of the object represents the inclination between the vertices. By using this information for the calculation of texture coordinates, as shown in FIG. 3, the pattern of the tone texture is related to the shape of the surface of the object. Can be transformed according to the direction component and the length component of the normal vector. More specifically, in accordance with the above equation (1A), the absolute value of the coordinate component of the normal vector (the value obtained by converting the value range of the length component from −1.0 to 1.0 to 0.0 to 1.0) A texture coordinate is obtained by adding or subtracting a value obtained by multiplying the arbitrary adjustment value to the screen coordinates (vertex screen coordinates) of each vertex of the object. In addition, what is necessary is just to make an adjustment value into a positive value when performing an addition process, and making an adjustment value into a negative value when performing a subtraction process. Here, the normal vector coordinate component is converted into an absolute value by applying a normal vector length component that can take a range of −1.0 to 1.0 to the deformation of the tone texture pattern as it is. This is because the degree of deformation of the pattern is too large in the case of expression. In this way, as shown in FIG. 4, the tone texture pattern is greatly deformed with respect to the direction of the normal vector, and the tone texture is mapped with a pattern along the shape of the object represented by the object. The three-dimensional effect can be expressed sufficiently.

  In this embodiment, the texture coordinates of the texture mapped to the object are the screen coordinates of each vertex of the object (vertex screen coordinates) and the screen coordinates of the reference point set for the object (reference point screen coordinates). And using. “Reference point set for an object” means a primitive unit, a part object unit composed of a plurality of primitives (points B1 to B6 in FIG. 5A), or a model composed of a plurality of part objects. It is an arbitrary point set in object units (point B in FIG. 5B), and one vertex of a primitive, a part object, or a model object may be used as a reference point.

  For example, a primitive surface including vertices P1, P2, and P3 in which a tone texture (texture size: 128 pixels × 128 pixels) of a hatching pattern as shown in FIG. 6A is projected onto the screen position shown in FIG. 6B. Consider the case of mapping to.

  As shown in FIG. 6B, the screen coordinates of the vertices P1, P2, and P3 are (128, 64), (64, 192), and (192, 192), respectively. In the present embodiment, of the vertices P1 to P3, the vertex P1 is the reference point B, and based on the screen coordinates of each vertex including the reference point and the texture size (pixel information in a broad sense) of the tone texture, Texture coordinates for mapping the tone texture shown in FIG.

  Specifically, when the texture coordinates are obtained according to the above equation (2A), as shown in FIG. 6C, the texture coordinates of the vertex P1 serving as the reference point B are set to (0, 0), and the vertex P2, The texture coordinates of P3 are set to (−0.5, 1) and (0.5, 1).

  When texture mapping is performed based on the texture coordinates set in this way, the tone texture is repeatedly pasted to the screen coordinate system with the reference point B (vertex P1) as the origin, as shown in FIG. 7A. In the primitive surface PR, the pattern of the portion surrounded by the vertices P1 to P3 is reflected, and the tone texture is mapped as shown in FIG.

  Here, consider a case where the virtual camera is translated in the X-axis direction of the screen coordinate system. At this time, as shown in FIG. 8A, the screen coordinates of the primitive surface PR are changed, but the reference point B is set at the vertex P1. For this reason, even if the screen coordinates of each vertex are changed by the movement of the virtual camera, the texture coordinates are not changed, and as shown in FIG. 8B, the same pattern as in FIG. Are mapped.

  On the other hand, when a texture coordinate is obtained using one point (origin) of the screen coordinate system as a reference point as a comparative example, as shown in FIG. As the screen coordinates change, the texture coordinates also change. This is because the relative positional relationship between the reference point and each vertex is changed because the origin is not changed despite the movement of the virtual camera. In this case, when the tone texture is mapped based on the obtained texture coordinates, as shown in FIG. 9B, the mapped pattern changes so as to flow along with the movement of the virtual camera, and the generated image Causes unnaturalness.

  Therefore, by using the method of the present embodiment, as shown in FIG. 8B, even if the virtual camera moves in parallel, the tone texture pattern mapped to the object does not flow and high-quality image representation is realized. can do. For example, high-quality shadow expression can be realized in the case of handwritten image expression.

2.2 Texture Coordinate Distance Correction Method Each vertex of an object arranged in the object space has a distance difference in the Z-axis direction (depth direction) in the camera coordinate system (viewpoint coordinate system) as shown in FIG. Therefore, the vertex P1 of the object located in front of the reference point B has a large movement in the screen coordinate system, and the vertex P2 of the object located in the back side of the reference point B has a small movement in the screen coordinate system. Become. That is, a difference in motion occurs between the vertices P1 and P2 of the object according to the distance difference from the reference point B. For this reason, if the texture coordinates for mapping the tone texture according to the difference from the reference point B are obtained uniformly, for example, the degree of display change such as pattern expansion / contraction will be shifted and the image will not be displayed. Prone to naturalness.

  Therefore, in the present embodiment, focusing on the fact that the movement in the screen coordinate system differs according to the distance difference in the depth direction between each vertex P1, P2 of the object and the reference point B as described above, Accordingly, a distance correction method for correcting the texture coordinates is adopted. Specifically, the reference point screen coordinates are corrected according to the distance difference in the depth direction from the reference point for each vertex of the tone texture mapping target object, and based on the difference from the corrected reference point screen coordinates. Then, the texture coordinates are corrected for each vertex (see the above equation (5A)). That is, in this method, a virtual reference point is set for each vertex of the object to be mapped.

  At this time, the correction amount (degree of correction) is smaller as the vertex is closer to the depth direction from the reference point B, and the correction amount is larger as the vertex is farther from the reference point B in the depth direction. Correct the texture coordinates. The distance correction value d for determining the correction amount is, for example, between each vertex P1, P2 and the reference point B so that the distance difference in the depth direction between the reference point B and each vertex P1, P2 is reflected in the texture coordinates. It can be determined based on the ratio of the perspective division values (see the above equation (4A)). In this way, in the example shown in FIG. 10, the distance correction value d is smaller for the vertex P1 closer to the virtual camera (viewpoint) than the reference point B (d <1), and the vertex P2 farther from the virtual camera than the reference point B is reached. For, the distance correction value d increases (d> 1). By doing so, the deviation in the degree of change in the texture display due to the difference in motion between the reference point B and each of the vertices P1 and P2 when the virtual camera moves is reduced, and the degree of the change in the texture display is the virtual camera. High-quality image expression can be realized by appropriately following the movement of the image.

2.3 Handwritten animation-like expression method For example, in handwritten animation, an animator creates a frame image by handwriting, so that a slight shift of line drawing occurs between the frame images. In the present embodiment, in order to express the line drawing peculiar to the frame image of such handwritten animation, a motion correction value (variable) whose value changes randomly or periodically in the texture coordinates for mapping the tone texture. ) To change the texture coordinates randomly or periodically (see the above formula (6A)), and can express handwritten texture. The motion correction value can be changed according to at least one of time, viewpoint movement information, and a game event, for example. In particular, when the viewpoint moves, the frame image changes greatly, so by adding a motion correction value that changes in value according to the movement information of the viewpoint and changing the texture coordinates, the texture of the handwritten animation tone can be changed even with computer graphics. It can be expressed sufficiently.

3. Processing of this embodiment Next, a detailed processing example of this embodiment will be described with reference to the flowchart of FIG.

  First, as a premise process for applying the method of the present embodiment, it is preferable to divide the vertex data group of the object into a vertex list group of a certain number of vertices. For example, a vertex list with 24 vertices as one set is created. Each vertex list includes a reference point for obtaining texture coordinates when mapping the tone texture.

  In the method according to the present embodiment, the following processing routine is executed for each vertex list.

  (1) First, geometry processing is performed for each vertex and reference point included in the vertex list (step S10). That is, perspective projection conversion is performed on the vertex and the reference point in the screen coordinate system.

  (2) Next, the screen coordinates (vertex screen coordinates) of the vertices after the geometry processing and the screen coordinates (reference point screen coordinates) of the reference points are acquired (step S11).

  (3) Next, normal drawing is performed for each vertex in the vertex list (step S12). That is, normal shading processing and normal texture mapping processing are performed for each vertex included in the vertex list.

  (4) Next, texture coordinates for mapping the tone texture are obtained (step S13). Specifically, the texture coordinate A0 is obtained from the coordinates on the screen of each vertex. At this time, the coordinate A0 is obtained in consideration of the difference between the vertex screen coordinates and the reference point screen coordinates and the depth difference in the camera coordinate system between each vertex and the reference point.

  (5) Next, a process of changing the tone texture in accordance with the surface shape of the object to be mapped is performed (step S14). Specifically, texture coordinates are weighted with normal vectors in the camera coordinate system (viewpoint coordinate system) of each vertex in order to transform the pattern (pattern) shown in the tone texture to conform to the surface shape of the object. To do. More specifically, the normal vector of the camera coordinate system of each vertex is obtained, and the absolute value of the X and Y elements of the coordinate component of the normal vector is multiplied by an arbitrary magnification (adjustment value, correction coefficient), This is added to the texture coordinate A0 to obtain a coordinate A3. In addition, when the addition processing is performed when obtaining the texture coordinate A3, an arbitrary magnification (adjustment value, correction coefficient) multiplied by the absolute value of the X and Y elements of the coordinate component of the normal vector is set as a positive value. . On the other hand, when subtraction processing is performed when obtaining the texture coordinate A3, an arbitrary magnification (adjustment value, correction coefficient) multiplied by the absolute value of the X and Y elements of the coordinate component of the normal vector is set as a negative value. To do.

  (6) Next, a process of adding a motion adjustment value for changing (moving) the texture coordinates to the coordinates A3 is performed to calculate the coordinates A4 (step S15). Specifically, handwritten animation-like expression is realized by changing (moving) the texture coordinates randomly or periodically.

  (7) Next, the tone texture is mapped to the object based on the obtained texture coordinate A4 (step S16). At this time, the image in which the tone texture is mapped may be drawn in a buffer (a buffer different from the drawing buffer) different from the image in which the normal texture is mapped in the drawing process in step S12. In this case, synthesis processing of an image (original image) using a normal texture and an image (tone map image) using a tone texture can be performed by translucent processing.

  (8) It is determined whether all the vertices in the vertex list have been drawn (step S17). If the drawing processing for all the vertices has not been completed (N in step S17), the processing in steps S13 to S16 is repeated.

  (9) Eventually, the process is terminated on condition that all vertex lists have been drawn (Y in step S18).

4). Hardware Configuration FIG. 12 shows an example of a hardware configuration capable of realizing this embodiment. The main processor 900 operates based on a program stored in the DVD 982 (information storage medium), a program downloaded via the communication interface 990, a program stored in the ROM 950, and the like, and includes game processing, image processing, sound processing, and the like. Execute. The coprocessor 902 assists the processing of the main processor 900, and executes matrix operation (vector operation) at high speed. For example, when a matrix calculation process is required for a physical simulation for moving or moving an object, a program operating on the main processor 900 instructs (requests) the process to the coprocessor 902.

  The geometry processor 904 performs geometry processing such as coordinate conversion, perspective conversion, light source calculation, and curved surface generation based on an instruction from a program operating on the main processor 900, and executes matrix calculation at high speed. The data decompression processor 906 performs decoding processing of compressed image data and sound data, and accelerates the decoding processing of the main processor 900. Thereby, a moving image compressed by the MPEG method or the like can be displayed on the opening screen or the game screen.

  The drawing processor 910 executes drawing (rendering) processing of an object composed of primitive surfaces such as polygons and curved surfaces. When drawing an object, the main processor 900 uses the DMA controller 970 to pass the drawing data to the drawing processor 910 and, if necessary, transfers the texture to the texture storage unit 924. Then, the drawing processor 910 draws the object in the frame buffer 922 while performing hidden surface removal using a Z buffer or the like based on the drawing data and texture. The drawing processor 910 also performs α blending (translucent processing), depth cueing, mip mapping, fog processing, bilinear filtering, trilinear filtering, anti-aliasing, shading processing, and the like. When an image for one frame is written in the frame buffer 922, the image is displayed on the display 912.

  The sound processor 930 includes a multi-channel ADPCM sound source and the like, generates game sounds such as BGM, sound effects, and sounds, and outputs them through the speaker 932. Data from the game controller 942 and the memory card 944 is input via the serial interface 940.

  The ROM 950 stores system programs and the like. In the case of an arcade game system, the ROM 950 functions as an information storage medium, and various programs are stored in the ROM 950. A hard disk may be used instead of the ROM 950. The RAM 960 is a work area for various processors. The DMA controller 970 controls DMA transfer between the processor and the memory. The DVD drive 980 (which may be a CD drive) accesses a DVD 982 (which may be a CD) in which programs, image data, sound data, and the like are stored. The communication interface 990 performs data transfer with the outside via a network (communication line, high-speed serial bus).

  The processing of each unit (each unit) in this embodiment may be realized entirely by hardware, or may be realized by a program stored in an information storage medium or a program distributed via a communication interface. Also good. Alternatively, it may be realized by both hardware and a program.

  When the processing of each part of this embodiment is realized by both hardware and a program, a program for causing the hardware (computer) to function as each part of this embodiment is stored in the information storage medium. More specifically, the program instructs the processors 902, 904, 906, 910, and 930, which are hardware, and passes data if necessary. Each processor 902, 904, 906, 910, 930 realizes the processing of each unit of the present invention based on the instruction and the passed data.

  The present invention is not limited to that described in the above embodiment, and various modifications can be made. For example, terms (pattern images, viewpoint coordinate systems, variables, etc.) cited as broad or synonymous terms (tone texture, camera coordinate system, motion correction value, normal vector, texture size, etc.) in the description or drawings. Normal vectors, pixel information, and the like) can be replaced with terms having a broad meaning or the same meaning in other descriptions in the specification or the drawings.

  Also, the texture coordinate calculation method, the texture coordinate distance correction method, the handwritten animation tone expression method, and the texture coordinate shape correction method are not limited to those described in the present embodiment, and methods equivalent to these are also described. It is included in the scope of the invention.

  The present invention can also be applied to various games (such as fighting games, shooting games, robot fighting games, sports games, competitive games, role playing games, music playing games, dance games, etc.). Further, the present invention is applied to various image generation systems such as a business game system, a home game system, a large attraction system in which a large number of players participate, a simulator, a multimedia terminal, a system board for generating a game image, and a mobile phone. it can.

The example of a functional block diagram of the image generation system of this embodiment. Explanatory drawing of the conventional method. Explanatory drawing of the method of this Embodiment. Explanatory drawing of the method of this Embodiment. 5A and 5B are explanatory diagrams of the method of this embodiment. FIG. 6A to FIG. 6C are explanatory diagrams of the method of this embodiment. FIG. 7A to FIG. 7C are explanatory diagrams of the method of this embodiment. FIG. 8A and FIG. 8B are explanatory diagrams of the method of this embodiment. FIGS. 9A and 9B are explanatory diagrams of the method of the comparative example. Explanatory drawing of the method of this Embodiment. The flowchart of the specific process of this embodiment. Hardware configuration example.

Explanation of symbols

100 processing unit,
110 Object space setting unit, 112 Movement / motion processing unit,
114 virtual camera control unit, 116 screen coordinate acquisition unit,
118 texture coordinate changing section,
120 image generation unit,
122 geometry processing unit, 124 texture mapping unit,
126 translucent processing section,
140 sound generation unit, 160 operation unit,
170 storage unit,
172 main storage unit, 174 drawing buffer, 176 texture storage unit 180 information storage medium, 194 portable information storage device,
190 Display unit, 192 Sound output unit, 196 Communication unit

Claims (8)

A program for generating an image viewed from a given viewpoint in an object space,
A geometry processing unit that performs perspective processing on the screen coordinate system to perform geometry processing;
A screen coordinate acquisition unit for acquiring the vertex screen coordinates of each vertex of the object after geometry processing;
A texture coordinate calculation unit that adds or subtracts normal vector information for each vertex of the object to the acquired vertex screen coordinates to obtain a texture coordinate for each vertex of the object;
As a texture mapping unit that maps a given texture to the object based on the determined texture coordinates,
A program characterized by causing a computer to function. In claim 1,
The program according to claim 1, wherein the normal vector information is obtained by converting a coordinate component of a normal vector of each vertex of the object in a viewpoint coordinate system or a screen coordinate system into an absolute value. In claim 2,
The normal vector information is obtained by multiplying an absolute value of a coordinate component of the normal vector by a given correction coefficient. In any one of Claims 1-3,
The screen coordinate acquisition unit
In addition to the vertex screen coordinates, obtain a reference point screen coordinate for a reference point set for the object,
The texture coordinate calculation unit is
Adding or subtracting normal vector information for each vertex of the object to the difference between the vertex screen coordinates and the reference point screen coordinates to obtain texture coordinates for each vertex of the object A program characterized by In any one of Claims 1-4,
The texture coordinate calculation unit is
A program for correcting the texture coordinates according to a distance difference in a depth direction in a viewpoint coordinate system between each vertex of the object and the reference point. In any one of Claims 1-5,
The texture coordinate calculation unit is
A program characterized in that a variable that changes randomly or periodically is added to the texture coordinates to change the texture coordinates.   An information storage medium readable by a computer, wherein the program according to any one of claims 1 to 6 is stored. An image generation system for generating an image viewed from a given viewpoint in an object space,
A geometry processing unit that performs perspective processing on the screen coordinate system to perform geometry processing;
A screen coordinate acquisition unit for acquiring the vertex screen coordinates of each vertex of the object after geometry processing;
A texture coordinate calculation unit for adding or subtracting normal vector information for each vertex of the object to obtain the texture coordinates for each vertex of the object;
A texture mapping unit for mapping a given texture to the object based on the determined texture coordinates;
An image generation system comprising:

Images